Membrane roof systems typically refer to roof decks covered with a water impermeable sheet of polymeric material such as ethylene propylene diene rubber (EPDM), chlorinated polyethylene, polyvinyl chloride, or chlosuffanated polyethylene. These roof systems are formed by covering a roof deck with a single ply of roofing membrane The roof membrane is typically held to the roof in one of several ways. For example, the entire roof membrane can be secured using adhesives. Alternately, the membrane can be secured solely with ballast Another approach is to secure the membrane using penetrating or nonpenetrating mechanical fasteners.
As disclosed in U.S. Pat. No. 4,649,686 entitled "High Wind Resistant Membrane Roof System" the wind uplift forces are not evenly distributed throughout the roof. The perimeter of a roof particularly next to a parapet wall encounters higher wind uplift forces than are encountered in the field of the roof. A parapet wall is a wall extending directly above the roof deck generally at its perimeter
One typical way of securing a membrane to a roof at a parapet wall is to use a batten bar fastening the membrane to the roof deck at the foot of the parapet wall. Flashing is adhered to the membrane covering the batten bar and also to the parapet wall This has been found to be particularly effective. Unfortunately this method is labor intensive and consequently quite expensive.
Another method typically used is to run a continuous sheet of field membrane as wall flashing. In other words, run the field membrane up the wall and adhere it to the side of the wall. This unfortunately is unsatisfactory because of the high uplift forces that are encountered at the perimeter of a roof. This could cause the membrane to separate from the parapet wall.